Packet switched networks such as Internet Protocol (IP) networks are widely used for communication. For example, packet switched networks are well-suited to delivering messages such as emails or other messages from a device in a public network, such as the Internet, to a target device, such as a mobile device or user equipment in a cellular, wireless, or private network.
One approach for facilitating packet switched communications in networks, such as cellular networks, involves General Packet Radio Service (GPRS). GPRS is a service facilitating communication between mobile devices in a cellular network, such as a GSM network, and devices accessible via a public IP-based network, such as the Internet. GPRS includes a GPRS core network which operates as an intermediate service network between the public IP-based network and the cellular network.
In some instances, it is desirable to use GPRS to communicate data from a server in the public network to a specified target device in the cellular network, without the target device having to specifically request the data. For example, it may be desirable to have the server substantially initiate a communication with the target device to send information related to an event, such as receipt of an email, an instant message, an online auction event, or the like. Such a communication is referred to herein as a push communication. Push communication may desirably reduce overhead in the network, since the target devices may not be required to periodically poll the server to retrieve pending messages held in the server.
One approach to providing push communication to devices in a cellular network, operatively coupled to a public network via a service network such as a GPRS core network, is to assign a public IP address to each potential target device in a cellular network. Each target device is thereby effectively made part of the public network. IP address assignments are made in response to an initial Packet Data Protocol (PDP) context activation initiated by the target device. A PDP context activation is an operation associated with GPRS which establishes an association between the target device and an IP address for use thereby. After a public IP address is assigned to the target device, it remains assigned to that device for at least a predetermined period of time, even if the target device subsequently performs a PDP context deactivation. Public IP address assignments may be configured to persist for a long period of time, for example days or weeks. Therefore, subsequent PDP context activations, occurring before expiry of the public IP address assignment, will re-establish the previous association between public IP address and target device. For push communications, the GPRS core network is configured to initiate a subsequent PDP context activation upon receipt of one or more packets addressed to the public IP address, if an appropriate PDP context is not currently active.
The above-described approach for providing push communications to a target device previously associated with a public IP address is illustrated in FIG. 1, and described as follows. Upon initiation of a push communication from a server 110 to a target device 130, the server 110 transmits one or more IP packets 115, each having an IP address corresponding to a public IP address previously assigned to the target device 130 during initial setup. The Gateway GPRS Support Node (GGSN) 120 receives the IP packets 115 and forwards them to the target device 130, via an appropriate Serving GPRS Support Node (SGSN) 125 and other appropriate network equipment, such as a cellular base station. If a PDP context is not activated for the target device, the GGSN initiates a PDP context activation for the target device, using the previously assigned public IP address.
However, since public IP addresses are a limited resource, it may not be feasible to support push communication for a large number of target devices in this manner at the same time.
Therefore there is a need for a method and apparatus for facilitating push communication across a network boundary that is not subject to one or more limitations in the art.
This background information is provided for the purpose of making known information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.